A commonly occurring configuration in automatically switched manual gearboxes is that respective gears are engaged or disengaged by moving an engagement element, usually in the form of a shaft. The engagement element has a notch or yoke-like shoulder acted upon by a shift finger which engages in the notch and pushes the engagement element in the respective direction for engagement or disengagement of the gear.
The shift finger effects this movement by being pivoted about a rotary shaft. This entails the shift finger and the pivoting operating shaft being first moved axially so that the shift finger is located axially to the position for cooperation with the respective engagement shaft.
The axial movement of the rotary shaft with the shift finger involves the application of a relatively large force, normally by use of pneumatic or hydraulic power means. Gear changing therefore tends to be cumbersome and imprecise.
Gearboxes of this kind are described inter alia in US 20040154419, US 20020189388, US 2001037698 and FR 2860567.
US20040154419A1 describes a mechanism for gearbox operation whereby a solenoid or an electric motor pivots a shaft and a pulling solenoid which can turn away the shift fingers, two or more fingers in a package, depending on which gear is to be engaged in the gearbox. The turning away is to prevent any double gear change, i.e. simultaneous engagement of two selector shafts. The turning away takes place axially along the selector shaft which transmits a pivoting movement and an axial movement.
US20020189388A1 is a gear change mechanism based entirely on solenoids and only one shift finger and using solenoids to switch the shift finger to seven different positions. There are three solenoids to effect this switching.
US2001037698 describes a shift finger which is pivoted by solenoids.
FR 2860567 describes a number of shift fingers which can be engaged individually relative to one another, with a slide which prevents an incorrect gear from being engaged when the others are to be operated, a kind of locking slide.
The object of the present invention is to propose an operating device of the kind here concerned whereby the disadvantages described above are eliminated, which device thus makes it possible for engagement and disengagement of a gear to take place more smoothly and simply than is possible in the state of the art.